Changing Fashions Changing Mates

Bunting mating habits

08-01-2008
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Hannah Schardt

FEMALE LARK BUNTINGS--medium-sized sparrows that breed throughout the Midwest--show strong preferences for males with certain physical traits. But in a surprising twist to evolutionary theory, researchers at the University of California-Santa Cruz have discovered that those preferences change from year to year. Lark buntings mate and share parenting responsibilities with different partners each year. The study, published in the journal Science, finds that females as a group might show a preference one year for males with larger wing patches, then the next year for males with smaller patches. "One possibility is that certain traits are associated with the male being a good forager, and other traits predict how well he could defend the nest from predators," says study coauthor Alexis Chaine. So in a year where nest predators are abundant, females would opt for male defenders over foragers, and when food is sparse, they would choose to mate with better foragers.